Project I is an integral component of a large research program on the neurocognitive functional deficits of learning disabled children. Its primary aims are (l) to identify "physiologically plausible" variables of temporal information processing that will discriminate efficiently between learning disabled and normally achieving children; and (2) on the basis of these experimental variables, to define profiles of functional deficits and strengths that characterize subgroups of learning disabled children. Two hundred learning disabled children from 8-11 years who meet specified inclusion and exclusion criteria, and a comparable standardization group of normally achieving children will be examined on low level variables of high frequency temporal information processing in auditory and visual perception and fine motor coordination, as well as on neurocognitive measures of sequence learning and visual filtering of figure-ground relationships. The findings from Project I will also serve as points of departure for other projects of the overall program.